Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true and openWorldHint=false, and the description reinforces this with 'it changes nothing and moves no money.' It adds genuinely non-structured information: the authentication requirement that cases opened with an organisation's key need that key. It stops short of describing error behavior, pagination, or what happens when a case has expired.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is front-loaded with the action and identifier, then the returned content, then the usage rule and safety/auth constraints. The middle enumeration of Evidence Passport sub-fields is dense but each item conveys what the agent will see; little is wasted.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description carries the burden of explaining return values, and it does so thoroughly by listing the case sections the agent receives. Auth and read-only behavior are covered. Only edge details such as missing-case handling or size of the timeline are absent, which is minor for a one-parameter read tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

There is a single parameter with 100% schema description coverage, so the schema already carries the load. The description restates the pi_… prefix that the schema itself documents and adds no format or sourcing detail beyond it; baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a specific verb and resource ('Read a payment case by intent_id') and then enumerates the concrete payload: lifecycle status, reporter, Evidence Passport contents, unknowns, exceptions with owner/next action, and timeline. That is far more specific than a tautology. It does not, however, differentiate itself from closely named siblings such as intent_status, payment_intent, or private_payment_status, leaving the agent to infer the distinction.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

'Use it before acting on a payment, to see what is current, what has expired and what must happen next' gives a clear triggering condition and purpose. No explicit exclusions or named alternatives are provided, so the agent gets context but not routing guidance against the many sibling status tools.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.